Optical communication systems typically involve each optical fiber including signals transmitted in a single direction. Accordingly two different optical fibers are used for two-way transmission between transceivers. Prior art methods for determining propagation delay would measure the round trip delay by sending a signal from a first transceiver to the second transceiver in one direction using one optical fiber, and receiving a reply from the second transceiver to the first transceiver in the return direction on another optical fiber. Such a method can measure the round trip propagation delay. However these two different fibers typically have different lengths, and therefore different propagation delays for signals that traverse the two optical fibers.
Next generation of wireless networks are expected to utilize optical fibers to connect transceivers at antennas to transceivers at base stations or cloud radio access network (C-RAN) data centers.
As communication systems become faster, by transmitting larger amounts of data per unit time interval, propagation delays between transmitting and receiving transceivers become more relevant. For example, an optical fiber of 2 m in length can introduce more than 10 nanoseconds (nsec) of propagation delay. However, it is expected that next generation of wireless networks that utilize optical backhauls from an antenna to a base station (or from a remote radio head to a C-RAN cluster) will have synchronization requirements in the order +/−8 nsec. In such a system the difference in lengths between the two optical fibers used for the two directions between the transceivers can exceed these synchronization requirements.
Accordingly, there is a need for a system and method that at least partially addresses one or more limitations of the prior art.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.